History and timing of human impact on Lake Victoria, East Africa

Proc Biol Sci. 2002 Feb 7;269(1488):289-94. doi: 10.1098/rspb.2001.1850.


Lake Victoria, the largest tropical lake in the world, suffers from severe eutrophication and the probable extinction of up to half of its 500+ species of endemic cichlid fishes. The continuing degradation of Lake Victoria's ecological functions has serious long-term consequences for the ecosystem services it provides, and may threaten social welfare in the countries bordering its shores. Evaluation of recent ecological changes in the context of aquatic food-web alterations, catchment disturbance and natural ecosystem variability has been hampered by the scarcity of historical monitoring data. Here, we present high-resolution palaeolimnological data, which show that increases in phytoplankton production developed from the 1930s onwards, which parallels human-population growth and agricultural activity in the Lake Victoria drainage basin. Dominance of bloom-forming cyanobacteria since the late 1980s coincided with a relative decline in diatom growth, which can be attributed to the seasonal depletion of dissolved silica resulting from 50 years of enhanced diatom growth and burial. Eutrophication-induced loss of deep-water oxygen started in the early 1960s, and may have contributed to the 1980s collapse of indigenous fish stocks by eliminating suitable habitat for certain deep-water cichlids. Conservation of Lake Victoria as a functioning ecosystem is contingent upon large-scale implementation of improved land-use practices.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Africa, Eastern
  • Agriculture
  • Anaerobiosis
  • Animals
  • Biological Evolution
  • Cichlids / physiology
  • Cyanobacteria / physiology
  • Diatoms / physiology
  • Ecosystem*
  • Eutrophication
  • Fresh Water / microbiology*
  • Fresh Water / parasitology*
  • Human Activities
  • Humans
  • Oxygen / metabolism
  • Paleontology
  • Phytoplankton / physiology
  • Population Growth


  • Oxygen